1. Field of the Invention
The present invention relates to crash-safe vehicle brake assembly designed to not only minimize intrusion of the assembly into the occupant compartment of the vehicle, but also to bias the movement of the brake pedal away from the driver in the event of a front impact collision.
2. Background of the Invention
Power brake assemblies for vehicles are by necessity generally mounted proximate the lower dash panel with the master cylinder, fluid reservoir, and booster on the engine compartment side and the brake pedal itself on the occupant compartment side of the lower dash panel. In the event of a front impact collision, components in the engine compartment are pushed rearward toward the occupant compartment, and in many cases the larger components of the brake assembly may themselves intrude into the occupant compartment, or cause the brake pedal and attendant linkages to move toward the driver and cause injury. Since many front impact collisions occur when the driver is trying to stop the vehicle and therefore the driver's foot is firmly applied to the brake pedal, significant rearward movement of the pedal itself or other brake assembly components is likely to injure the driver's foot and/or leg.
A schematic illustration of a conventional brake assembly before a frontal crash is shown in FIG. 1, and after a frontal crash is shown in FIG. 2. In these figures, dash lower panel D divides the engine compartment EC from the occupant compartment OC with master cylinder M and booster B mounted just inside engine compartment EC, and coupled to brake pedal P which is disposed inside the occupant compartment OC. The arrow in FIG. 1 shows the rearward direction of the force transmitted in a frontal crash. A component C in the engine compartment, such as the battery for example, is driven into master cylinder M. FIG. 2 schematically illustrates the position of the assembly pre-crash in solid lines and post-crash in dashed lines. When component C contacts master cylinder M, the force of the impact tends to move the brake assembly toward occupant compartment OC and brake pedal P upward. As noted previously, in a frontal crash it is likely that the driver has his or her foot firmly planted on the brake pedal. It is can be seen that the upward movement of the brake pedal can increase the possibility of injury to the driver.
There have been numerous previous attempts to address this problem. In one approach, various brackets, linkages or fasteners in the brake assembly are designed to fail upon frontal impact to, in essence, disconnect the engine compartment components from the brake pedal. U.S. Pat. No. 6,079,207 to Stadler et al., U.S. Pat. No. 6,339,971 to Kato; and U.S. Pat. No. 6,481,311 to Sanagi et al. disclose breakaway fastener concepts. U.S. Pat. No. 6,2969,900 to Adams et al.; and U.S. Patent Publication No. 2003/0075005 to Schiel et al. disclose linkages in a brake assembly which are designed to redirect the force of a frontal crash.
In another approach to the problem, other components are designed to fail to lessen the severity of a frontal crash. U.S. Pat. No. 5,531,135 to Dolla discloses a pedal arrangement in which the bulkhead is weakened at a buckle zone. Upon frontal impact the bulkhead buckle zone crumples and carries the bearing mounts and pedals with it away from the driver. Japanese Patent No. 11105737 to Tomonori also discloses a structural change to the engine compartment to inhibit intrusion of the brake components into the occupant compartment. A strut tower is designed with an inclined face to bear against the master cylinder upon impact and thereby cause the master cylinder to rotate upward.
U.S. Pat. No. 6,041,601 to Verbo et al. discloses a brake assembly mounted horizontally with a booster case having a multiple part front shell designed to separate and collapse in a crash to absorb the kinetic energy. U.S. Pat. No. 6,301,886 to Kaneko et al. also discloses a planned failure of the booster case caused by a specially designed diamond-shaped coupling flange on the master cylinder contacting and breaking through a booster shell wall that is weakened in a selected area. The coupling flange has an arc-shaped tip that is designed to break through the booster shell wall. Kaneko et al. also requires a specially designed reinforcing plate mounted inside the booster case on the master cylinder side. The reinforcing plate has a notched area through which the arc-shaped tip of the coupling flange passes through. Because the reinforcing plate rigidifies most of this inside assembly, the movement of the coupling flange through the notched area causes the master cylinder to break into the booster and incline. The goal of Kaneko et al. is to prevent movement of the push rods, pedals, etc. in the crew compartment when an external force is applied to the hydraulic pressure generating apparatus in the engine compartment. Another measure taught by Kaneko et al. to prevent movement of the valve housing, push rod and pedal is to incline booster and master cylinder upward with respect to the horizontal. Kaneko et al. requires the specially designed coupling flange to be positioned proximate the booster shell, and the specially designed mating reinforcing plate to be assembled inside the booster in order to achieve the goal of preventing movement of the pedal, push rods and other components inside the crew compartment.
The prior art examples discussed herein focus on either the engine compartment portion of the brake assembly, or the passenger compartment portion. That is, some address the need to prevent the engine compartment portion from intruding into the passenger compartment by way of breakaway fasteners or other parts failures that operably disconnect the engine compartment portion from the pedal. Others address the need to move the brake pedal, also by way of breakaway fasteners and the like. The prior attempts to design a brake assembly that reduces the possibility of injury to the driver in a frontal crash required a multiplicity of specially designed parts such as brackets with guide surfaces, linkages designed for failure, coupling flanges designed to collapse into a booster case, and reinforcing plates for rigidifying a booster case with complex configurations. Additional parts mean increased complexity, weight and higher costs of manufacture. Even with these complex assemblies and additional parts, the prior art does not address advantageous movement of both the engine compartment portion causing movement of the passenger compartment portion in response to a collision force.
There has been a need for a crash-safe brake assembly that reduces the amount of intrusion into the occupant compartment in the event of a crash. Not only that, but also recognition that since the driver's foot is likely already pressed to the brake during a frontal crash, there has been a need for a brake assembly that purposefully moves the brake pedal away from the driver to prevent injuries to the foot and/or leg.